Simple Two-way Active Measurement Protocol Extensions for Hop-by-Hop OAM Data Collection
draft-wang-ippm-stamp-hbh-extensions-00

Abstract

This document defines optional TLVs which are carried in Simple Two-way Active Measurement Protocol (STAMP) test packets to enhance the STAMP base functions. Such extensions to STAMP enable OAM data collection at every node that STAMP test packets traverse.

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

Status of This Memo

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This Internet-Draft will expire on January 11, 2021.

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Table of Contents

• 1. Introduction
• 2. Terminology
• 3. TLV Extensions to STAMP
• 3.1. IOAM Tracing Data TLV
• 3.2. Forward HbH Delay TLV
• 3.3. Backward HbH Delay TLV
• 4. IANA Considerations
• 5. Security Considerations
• 6. References
• 6.1. Normative References
• 6.2. Informative References
• Authors' Addresses

1. Introduction

Simple Two-way Active Measurement Protocol (STAMP) enables the measurement of both one-way and round-trip performance metrics, such as delay, delay variation, and packet loss [RFC8762]. In the STAMP session, the bidirectional packet flow is transmited between STAMP Session-Sender and STAMP Session-Reflector. The STAMP Session-Reflector receives packets transmited from Session-Sender and acts according to the configuration. However, the performance of intermediate nodes that STAMP test packets traverse are invisible. And the STAMP instance must be configured at every intermediate node to measure the performance per node that test packets traverse, which increases the complexity of OAM in large-scale networks.

This document extents optional TLVs to STAMP which enable OAM data collection at every node that STAMP test packets traverse, such as measurement of delay, packet loss, delay variation per hop, and record of route information. STAMP Extensions have defined several optionnal TLVs to enhance the STAMP base functions. These optional TLVs are defined as updates of the STAMP Optional Extensions [I-D.ietf-ippm-stamp-option-tlv]. The following sections describe the use of TLVs for STAMP that extend STAMP capability beyond its base specification.

2. Terminology

Following are abbreviations used in this document:

STAMP: Simple Two-way Active Measurement Protocol.

IOAM: In-situ OAM.

HbH: Hop-by-Hop.

3. TLV Extensions to STAMP

3.1. IOAM Tracing Data TLV

STAMP Session-Sender MAY place the IOAM Tracing Data TLV in STAMP Session-Sender test packets to record the IOAM tracing data of every IOAM capable node that the STAMP Session-Sender test packet traverses in the forward path. As STAMP uses symmetrical packets, the Session-Sender MUST set the Length value as a multiple of 4 octets according to the number of intermediate nodes and the IOAM-Trace-Type (i.e. a 24-bit identifier which specifies which data types are used in the node data list [I-D.ietf-ippm-ioam-data]). And the node-data-copied-list fields MUST be set to zero upon Session-Sender test packets transmission and ignored upon receipt.

The IOAM Tracing Data TLV has the following format:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
|   IOAM-Tracing-Data Type      |            Length             |
+---------------------------------------------------------------+
|                    node data copied list [0]                  |
+---------------------------------------------------------------+
|                    node data copied list [1]                  |
+---------------------------------------------------------------+
~                               ...                             ~
+---------------------------------------------------------------+
|                    node data copied list [n]                  |
+---------------------------------------------------------------+

Fig. 1 IOAM Tracing Data TLV Format

where fields are defined as the following:

IOAM-Tracing-Data Type: To be assigned by IANA.

Length: A 2-octet field that indicates the length of the value field in octets and equal to a multiple of 4 octets dependent on the number of nodes and IOAM-Trace-Type bits.

node data copied list [0..n]: A variable-length field, which record the copied content of each node data element determined by the IOAM-Trace-Type. The order of packing the data fields in each node data element follows the bit order of the IOAM-Trace-Type field (see section 4.4.1 of [I-D.ietf-ippm-ioam-data]). The last node data element in this list is the node data of the first IOAM trace capable node in the path.

In an IOAM domain, the STAMP Session-Sender and the STAMP Session-Reflector MAY be configured as the IOAM encapsulating node and the IOAM decapsulating node. The STAMP Session-Sender (i.e. the IOAM encapsulating node) generates the STAMP test packet with the IOAM Tracing Data TLV. For applying the IOAM Trace-Option functionalities to the STAMP Session-Sender test packet, the STAMP Session-Sender must inserts the "trace option header" and allocate an node-data-list array [I-D.ietf-ippm-ioam-data] into "option data" fields of Hop-by-Hop Options header in IPv6 packets [I-D.ietf-ippm-ioam-ipv6-options], and sets the corresponding bits in the IOAM-Trace-Type. Also, the STAMP Session-Sender allocates an node-data-list array which is used to store OAM data retrieved from every IOAM transit nodes while the Session-Sender test packets traverse the path.

When the STAMP Session-Reflector (i.e. the IOAM decapsulating node) received the STAMP Session-Sender test packet with the IOAM-Tracing-Data TLV, it MUST copy the node-data-list array into the node-data-copied-list array carried in the reflected test packet before transmission and MUST remove the IOAM-Data-Fields. Hence, using IOAM-Tracing-Data TLV in STAMP testing enables hop-by-hop OAM data collection.

Also the STAMP Session-Reflector MAY be configured as IOAM encapsulating node to apply the IOAM Trace-Option functionalities to the reflected test packet. Hence, hop-by-hop OAM data collection can be also enabled for the backward path that the reflected packets traverse. When the reflected packet arrives at the Session-Sender receives, it can be either locally processed or sent to the centralized controller.

3.2. Forward HbH Delay TLV

STAMP Session-Sender MAY place the Forward HbH Delay TLV in Session-Sender test packets to record the ingress timestamp and engress timestamp at every intermediate nodes in the forward path that STAMP test packets traverse. The Session-Sender MUST set the Length value according to the number of intermediate nodes in the forward path and the timestamp formats. There are several methods to synchronize the clock, e.g., Network Time Protocol (NTP) [RFC5905]. For example, if a 64-bit timestamp format defined in NTP is used, the Length value MUST be set as a multiple of 8 octets. The Timestamp Tuple list (Ingress Timestamp [0..n], Engress Timestamp [0..n]) fields MUST be set to zero upon Session-Sender test packets transmission and ignored upon receipt.

The Forward HbH Delay TLV has the following format:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+---------------+---------------+
|   Forward HbH Delay Type      |     Length    |    Node Left  |
+-------------------------------+---------------+---------------+
|                     Ingress Timestamp [0]                     |
|                                                               |
+---------------------------------------------------------------+
|                     Engress Timestamp [0]                     |
|                                                               |
+---------------------------------------------------------------+
~                              ...                              ~
+---------------------------------------------------------------+
|                     Ingress Timestamp [n]                     |
|                                                               |
+---------------------------------------------------------------+
|                     Engress Timestamp [n]                     |
|                                                               |
+---------------------------------------------------------------+

Fig. 2 Forward HbH Delay TLV Format

where fields are defined as the following:

Forward HbH Delay Type: To be assigned by IANA.

Length: A 8-bit field that indicates the length of the value portion in octets and MUST be a multiple of 8 octets according to the number of intermediate nodes in the forward path.

Node Left: A 8-bit unsigned integer, which indicates the number of intermediate nodes remaining. That is, number of exlicitly listed intermediate nodes still to be visited before reaching the destination node in the forward path. The Node Left field is set to n-1, where n is the number of intermediate nodes.

Timestamp Tuple list (Ingress Timestamp [0..n], Engress Timestamp [0..n]): A variable-length field, which record the timestamp when the Session-Sender test packet is received at the ingress of the n-th intermediate node and the timestamp when the Session-Sender test packet is sent at engress of the n-th intermediate node. For example, if a 64-bit timestamp format defined in NTP is used, the length of each Timestamp tuple (Ingress Timestamp [n], Engress Timestamp [n]) must be 16 octets. The Timestamp Tuple list is encoded starting from the last intermediate node which is exlicitly listed. That is, the first element of the Timestamp Tuple (Ingress Timestamp [0], Engress Timestamp [0]) records the timestamps when the Session-Sender test packet received and forwarded at the last intermediate node of a explicit path, the second element records the penultimate Timestamp Tuple when the Session-Sender test packet received and forwarded at the penultimate intermediate node of a explicit path, and so on.

In the following reference topology, Node N1, N2, N3, N4 and N5 are SRv6 capable nodes. Node N1 is the STAMP Session-Sender and Node N5 is the STAMP Session-Reflector. T1 is the Timestamp taken by the Session-Sender (i.e. N1) at the start of transmitting the test packet. T2 is the Receive Timestamp when the test packet was received by the Session-Reflector (i.e. N5). T3 is the Timestamp taken by the Session-Reflector at the start of transmitting the test packet. T4 is the Receive Timestamp when the test packet was received by the Session-Sender. Timestamp tuples (t1,t2), (t3,t4) and (t5,t6) are the timestamps when the test packet received and transmited by sequence of intermediate nodes in the forward path. Timestamp Tuples (t7,t8), (t9,t10) and (t11,t12) are the timestamps when the test packet received and transmited by sequence of intermediate nodes in the backward path.

======          ======          ======          ======         ======
|    | T1--->t1 |    | t2--->t3 |    | t4--->t5 |    | t6--->T2|    |
| N1 |==========| N2 |==========| N3 |==========| N4 |=========| N5 |
|    | T4<---t12|    |t11<---t10|    | t9<---t8 |    | t7<---T3|    |
======          ======          ======          ======         ======

Fig. 3 Reference Topology

The STAMP Session-Sender (i.e. Node N1) generates the STAMP test packet with the Forward HbH Delay TLV. When an intermediate node receives the STAMP test packet, the node sends the packet to control plane and fills the Ingress Timestamp [n] filed in the Forward HbH Delay TLV. Then the time taken by the intermediate node transmitting the test packet is recorded in to Engress Timestamp [n] field in the Forward HbH Delay TLV. The mechanism of timestamping and punting packet to control plane is outside the scope of this specification.

When the STAMP Session-Reflector received the test packet with the Forward HbH Delay TLV, it MUST copy the Forward HbH Delay TLV into the reflected test packet before its transmission. Using Forward HbH Delay TLV in STAMP testing enables hop-by-hop delay measurement in the forward path.

3.3. Backward HbH Delay TLV

STAMP Session-Sender MAY place the Backward HbH Delay TLV in Session-Sender test packets to record the ingress timestamp and engress timestamp when Session-Reflector test packets are received and sent at every intermediate nodes in the backward path. The Session-Sender MUST set the Length value according to the number of intermediate nodes in the backward path and the timestamp formats. There are several methods to synchronize the clock, e.g., Network Time Protocol (NTP) [RFC5905]. For example, if a 64-bit timestamp format defined in NTP is used, the Length value MUST be set as a multiple of 8 octets. The Timestamp Tuple list (Ingress Timestamp [0..n], Engress Timestamp [0..n]) fields MUST be set to zero upon Session-Sender test packets transmission and ignored upon receipt.

The Backward HbH Delay TLV has the following format:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+---------------+---------------+
|   Backward HbH Delay Type     |     Length    |    Node Left  |
+-------------------------------+---------------+---------------+
|                     Ingress Timestamp [0]                     |
|                                                               |
+---------------------------------------------------------------+
|                     Engress Timestamp [0]                     |
|                                                               |
+---------------------------------------------------------------+
~                              ...                              ~   
+---------------------------------------------------------------+
|                     Ingress Timestamp [n]                     |
|                                                               |
+---------------------------------------------------------------+
|                     Engress Timestamp [n]                     |
|                                                               |
+---------------------------------------------------------------+

Fig. 4 Backward HbH Delay TLV Format

where fields are defined as the following:

Backward HbH Delay Type: To be assigned by IANA.

Length: A 8-bit field that indicates the length of the value portion in octets and will be a multiple of 8 octets dependent on the number of nodes in a path.

Node Left: A 8-bit unsigned integer, which indicates the number of intermediate nodes remaining. That is, number of exlicitly listed intermediate nodes still to be visited before reaching the destination node in the backward path. The Node Left field is set to n-1, where n is the number of intermediate nodes.

Timestamp Tuple list (Ingress Timestamp [0..n], Engress Timestamp [0..n]): A variable-length field, which record the timestamp when the reflected test packet is received at the ingress of the n-th intermediate node and the timestamp when the reflected test packet is sent at engress of the n-th intermediate node. For example, if a 64-bit timestamp format defined in NTP is used, the length of each Timestamp tuple (Ingress Timestamp [n], Engress Timestamp [n]) must be 16 octets. The Timestamp Tuple list is encoded starting from the last intermediate node which is exlicitly listed. That is, the first element of the Timestamp Tuple (Ingress Timestamp [0], Engress Timestamp [0]) records the timestamps when the reflected test packet received and forwarded at the last intermediate node of a explicit path, the second element records the penultimate Timestamp Tuple when the reflected test packet received and forwarded at the penultimate intermediate node of a explicit path, and so on.

When the STAMP Session-Reflector received the Session-Sender test packet with the Backward HbH Delay TLV, it MUST copy the Backward HbH Delay TLV into the reflected test packet.

When an intermediate node receives the reflected test packet, the node sends the packet to control plane and fills the Ingress Timestamp [n] filed of Backward HbH Delay TLV. Then the time taken by the intermediate node transmitting the test packet is recorded in to Engress Timestamp [n] field of Backward HbH Delay TLV. Using Backward HbH Delay TLV in STAMP testing enables hop-by-hop delay measurement in the backward path.

4. IANA Considerations

IANA is requested to allocate values for the following TLV Type from the "STAMP TLV Type" registry [I-D.ietf-ippm-stamp-option-tlv].

5. Security Considerations

This document introduces new TLV extensions to STAMP. It does not introduce any new security risks to STAMP.

6. References

6.1. Normative References

6.2. Informative References

Authors' Addresses